CS 25.975 Fuel tank vents

• ED Decision 2018/005/R found in: CS-25 Amdt 27 - Large Aeroplanes (Jan 2023)

CS 25.975 Fuel tank vents ED Decision 2018/005/R (a) *Fuel tank vents*. Each fuel tank must be vented from the top part of the expansion space so that venting is effective under any normal flight condition. In addition – (1) Each vent must be arranged to avoid stoppage by dirt or ice formation; (2) The vent arrangement must prevent siphoning of fuel during normal operation; (3) The venting capacity and vent pressure levels must maintain acceptable differences of pressure between the interior and exterior of the tank, during – (i) Normal flight operation; (ii) Maximum rate of ascent and descent; and (iii) Refuelling and defuelling (where applicable); (4) Airspaces of tanks with interconnected outlets must be interconnected; (5) There may be no point in any vent line where moisture can accumulate with the aeroplane in the ground attitude or the level flight attitude, unless drainage is provided; (6) No vent or drainage provision may end at any point: (i) Where the discharge of fuel from the vent outlet would constitute a fire hazard; or (ii) From which fumes could enter personnel compartments; and (7) Each fuel tank vent system must prevent explosions, for a minimum of 2 minutes and 30 seconds, caused by the propagation of flames from outside the tank through the fuel tank vents into the fuel tank vapour spaces when any fuel tank vent is continuously exposed to flames. (See [AMC 25.975(a)(7)](#_DxCrossRefBm1709821457)) [Amdt 25/21]